Ion Channels And Hyper Flashcards
Major intracellular and extracellular ions
K and Na
Monovalent cations
Na and K
Divalent cations
Ca and Mg
Ionic gradient
More K inside and Na outside
Ion channels
Membrane proteins that allow contorted movement of charged ions across the cell membrane
Ion channel properties
Membrane pores
Ionotropic receptors
Gates
Ion selectivity
Types of gated channels and what they are activated by
Voltage gated - voltage
Ligand gates - ligands (intra and extraellular)
Mechanically gated - force in plasma membrane `
Ligand gates ion channel structure
Single subunit architecture :
- Transmembrane domains
- N and C terminal
- Lops link the TM domains together
Assembled architecture :
- multi subunit composition (Can have different numbers of subunits which help categorise into different categories/families )
- pentameric, tetrameric or trimeric
Ligand gated ion channel families
Cys-loop family
- nicotine acetylcholine receptor
Other
- glutamate receptors
Voltage gated ion channel
Transmebrane potential exist across plasma membrane
Inside cell is negative
Voltage gates have multiple domains
One domain is the voltage sensor - detect electrical change and rotation opens the channel pore
Voltage gated at -70mV, -50 to +30mv and +30mv to -50mv
-70mV - > closed and no Na can get through
-50 to +30mv -> open and starts to depolarise
+30mv to -50mv -> inactive. Doesn’t stay open long and conduct enough Na to depolarise the cell. Ball and chain blocks ion conduction
In alpha one how many TMD
24 organised into 4 repeating segments, each with 6 domains
1s1, 1s2, 1s3, 1s4. 1s5, 1s6
2s1, 2s2, 2s3, 2s4, 2s5, 2s6
3s1, 3s2, 3s3, 3s4, 3s5, 3s6
4s1, 4s2, 4s3, 4s4, 4s5, 4s6
A1 subunit
Is the channel pore, there will be no hole it eh middle without it
Several different A1 exist and are known as different CaV (CaV1, CaV2)
Auxhillary subunits
B, Y and a2-s
They are like friends forming a group and cannot have a channel without the all
They help the a1 subunit get to the membrane like a police escort and they regulate ion channel properties
Voltage gated K channels again families
Kv and inward rectifying channels
Different structure to NaV and CaV
Each Kv subunit has 6 TMD
4x a subunits come together as a tetramer